The Manchester United manager left the Englishman on the bench when he gave the Dutchman his full debut in last Saturday's 3-2 win over Fulham, fuelling suggestions that there was only room for one as the spearhead of his side.

And with Rooney now injured, the duo, who scored 71 goals between them last season, cannot be paired just yet. But the Scot is certain both can fit into his new-look 4-2-3-1 formation along with Danny Welbeck.

"Yes, absolutely," Ferguson said, when asked if he would play both together. "There's no doubt about that. And Welbeck can play with them, there is no question about that. I have good options. That is where it is going to be difficult."

When Ferguson signed Van Persie he compared his modern-day quartet of strikers, including Javier Hernandez, with the four forwards who propelled his side to a Treble in 1999 - Andy Cole, Dwight Yorke, Teddy Sheringham and Ole Gunnar Solskjaer.

"For strikers it's definitely more difficult than 1999," he added. "Then, Yorke and Cole developed an incredible partnership so they were always my two main ones. If we wanted to give them a break, Sheringham or Solskjaer would come in. We were very lucky with those four.

"Van Persie is flexible because he can play in different positions, from the right, in behind the strikers. He is such a mobile player, there are great options with him. And Wayne can play behind and he can play up. Chicharito [Hernandez] is the only one-position player and that is through the middle."

But Ferguson has warned Rooney that he has a difficult task controlling his weight, comparing the stocky striker with the slighter 38-year-old Ryan Giggs.

"Wayne is no Ryan Giggs," he explained. "Ryan has never put a pound on in his whole life. Wayne is a boy that needs games, you can see that from the frame he's got. He is stocky, strong and really needs games, simple as that.

"Some people are lucky. I have had nights out with the jockey Mick Kinane, we've had three bottles of wine and he's still the same weight, not an ounce on him. Unbelievable, and his father Tommy is exactly the same."